Hi:
I founded some problems with puppy installation while doing it via the first option (distribution, select distribution, select version), but i solved it this way:
- First I download the puppy .iso image to my hard disk via puppy homepage
-Secondly I plug in the USB into an USB PORT
-Thirdly, I started UNetbootin and chose the second option (disk image, ISO, ... and search for the image)
- Finally.- I push OK and it's recorded successfully.
Try this way and it's possible it works for you too
HAVE A NICE DAY